Page 49 - A Guide to MATLAB for Beginners and Experienced Users

30 Chapter 2: MATLAB Basics

We describe more of MATLAB’s graphics commands in Chapter 5.
For now, we content ourselves withdemonstrating how to plot a pair of
expressions on the same graph.

Plotting Multiple Curves
Eachtime you execute a plotting command, MATLAB erases the old plot and
draws a new one. If you want to overlay two or more plots, type hold on.
This command instructs MATLAB to retain the old graphics and draw any
new graphics on top of the old. It remains in effect until you type hold off.
Here’s an example using ezplot:
>> ezplot(’exp(-x)’, [0 10])
>> hold on
>> ezplot(’sin(x)’, [0 10])
>> hold off
>> title ’exp(-x) and sin(x)’
The result is shown in Figure 2-3 earlier in this chapter. The commands hold
on and hold off work withall graphics commands.
With plot, you can plot multiple curves directly. For example,

>> X = 0:0.1:10;
>> plot(X, exp(-X), X, sin(X))
Note that the vector of x coordinates must be specified once for eachfunction
being plotted.